1. Field
Embodiments relate to a light emitting module and a light emitting apparatus.
2. Background
A light emitting diode (LED) is a kind of semiconductor device that converts electricity into light, for example, infrared light, for signal transmission and reception or that is used as a light source, using the characteristics of a compound semiconductor.
Group III-V nitride semiconductors have been used as core materials for light emitting devices, such as, for example, light emitting diodes (LEDs) or laser diodes (LDs), due to the physical and chemical properties thereof.
LEDs are eco-friendly because they do not include environmentally harmful materials, such as mercury (Hg) used in conventional lighting apparatuses, e.g., incandescent lamps and fluorescent lamps. In addition, LEDs have long lifespans and low power consumption. For these reasons, LEDs have replaced conventional light sources.
Liquid crystal displays (LCDs) and plasma display panels (PDPs) are typically known as large-sized display apparatuses. Unlike the PDP, which is self-emissive, the LCD needs a backlight unit as the LCD is not self-emissive.
A backlight used in the LCD may include a light emitting device, a lens located on the light emitting device, and a diffusion plate located on the lens. Based on the position of a light source, the backlight unit may be classified as an edge-type backlight unit or a direct-type backlight unit.
In the edge-type backlight unit, the light source is located at the left and right sides and/or the upper and lower sides of an LCD panel, and light may be uniformly dispersed over the entire surface of the LCD panel using a light guide plate. As a result, light uniformity may be high, and the thickness of the LCD panel may be remarkably reduced.
In the direct-type backlight unit generally applied to display apparatuses larger than 20 inches, a plurality of light sources is located under a panel. The direct type backlight unit may exhibit higher light efficiency than the edge-type backlight unit. For this reason, the direct-type backlight unit may be mainly used for large-sized display apparatuses in which high luminance is critical. In addition, in the direct-type backlight unit, the size of a bezel may be more easily reduced than in the edge-type backlight unit.
In the direct-type backlight unit, light emitted from the light emitting device is spread using the lens and then exits through the diffusion plate. If a reflection plate is positioned to reflect light exiting from the lateral side of the light emitting device and to emit the reflected light to the upper side of the light emitting device, the brightness of light exiting from the edge of the diffusion plate is different from the brightness of light exiting from the center of the diffusion plate as a beam angle of light emitted from the light emitting device through the lens is different from an angle of inclination of the reflection plate. Thus, light uniformity may be reduced.